There are many degrees and kinds of wider and easier access to this literature. By 'open access' to this literature, we mean its free availability on the public internet, permitting any users to read, download, copy, distribute, print, search, or link to the full texts of these articles, crawl them for indexing, pass them as data to software, or use them for any other lawful purpose, without financial, legal, or technical barriers other than those inseparable from gaining access to the internet itself. The only constraint on reproduction and distribution, and the only role for copyright in this domain, should be to give authors control over the integrity of their work and the right to be properly acknowledged and cited.

For a work to be OA, the copyright holder must consent in advance to let users "copy, use, distribute, transmit and display the work publicly and to make and distribute derivative works, in any digital medium for any responsible purpose, subject to proper attribution of authorship....

In addition to removing access barriers, OA should be immediate, rather than delayed, and should apply to full-text, not just to abstracts or summaries.

Scholars write journal articles because advancing knowledge in their fields advances their careers. They write for impact, not for money. It takes nothing away from a disinterested desire to advance knowledge to note that it is accompanied by a strong self-interest in career-building. OA does not depend on altruistic volunteerism.

Peer review does not depend on the price or medium of a journal. Nor does the value, rigor, or integrity of peer review.

One reason we know that peer review at OA journals can be as rigorous and honest as peer review in conventional journals is that it can use the same procedures, the same standards, and even the same people (editors and referees) as conventional journals.

Conventional publishers sometimes object that one common funding model for OA journals (charging fees to authors of accepted articles or their sponsors) compromises peer review. I've answered this objection at length elsewhere.

OA journals can use traditional forms of peer review or they can use innovative new forms that take advantage of the new medium and the interactive network joining scholars to one another. However, removing access barriers and reforming peer review are independent projects. OA doesn't presuppose any particular model of peer review, and all the models of peer review that are compatible with print journals (and many more) are compatible with OA journals.

In most disciplines and most fields the editors and referees who perform peer review donate their labor, just like the authors. Where they are paid, OA to the resulting articles is still possible; it merely requires a larger subsidy than otherwise.

Despite the fact that those exercising editorial judgment usually donate their labor, performing peer review still has costs --distributing files to referees, monitoring who has what, tracking progress, nagging dawdlers, collecting comments and sharing them with the right people, facilitating communication, distinguishing versions, collecting data, and so on. Increasingly these non-editorial tasks are being automated by software, including open-source software.

The purpose of the campaign for OA is the constructive one of providing OA to a larger and larger body of literature, not the destructive one of putting non-OA journals or publishers out of business. The consequences may or may not overlap (this is contingent) but the purposes do not overlap.

Even though journal prices have risen four times faster than inflation since the mid-1980's, the purpose of OA is not to punish or undermine expensive journals, but to provide an accessible alternative and to take full advantage of new technology -the internet- for widening distribution and reducing costs. Moreover, for researchers themselves, the overriding motivation is not to solve the journal pricing crisis but to deliver wider and easier access for readers and larger audience and impact for authors.

Authors: OA gives them a worldwide audience larger than that of any subscription-based journal, no matter how prestigious or popular, and provably increases the visibility and impact of their work.

Readers: OA gives them barrier-free access to the literature they need for their research, not constrained by the budgets of the libraries where they may have access privileges. It increases their convenience, reach, and retrieval power. OA also gives barrier-free access to the software that assists readers in their research. Free online literature is free online data for software that facilitates full-text searching, indexing, mining, summarizing, translating, querying, linking, recommending, alerting, "mash-ups" and other forms of processing and analysis.

Teachers and students: OA puts rich and poor on an equal footing for these key resources and eliminates the need for permissions to reproduce and distribute content.

Libraries: OA solves the pricing crisis for scholarly journals. It also solves what I've called the permission crisis. OA also serves library interests in other, indirect ways. Librarians want to help users find the information they need, regardless of the budget-enforced limits on the library's own collection. University librarians want to help faculty increase their audience and impact and thereby help the university raise its research profile.

Universities: OA increases the visibility of their faculty and institution, reduces their expenses for journals, and advances their mission to share knowledge.

Journals and publishers: OA makes their articles more visible, discoverable, retrievable, and useful. If a journal is OA, then it can use this superior visibility to attract submissions and advertising, not to mention readers and citations. If a subscription-based journal provides OA to some of its content (e.g. selected articles in each issue, all back issues after a certain period, etc.), then it can use its increased visibility to attract all the same benefits plus subscriptions. If a journal permits OA through postprint archiving, then it has an edge in attracting authors over journals that do not permit postprint archiving. Of course subscription-based journals and their publishers have countervailing interests as well and generally oppose OA. But it oversimplifies the situation to think that all their interests pull against OA.

Funding agencies: OA increases the return on their investment in research, making the results of the funded research more widely available, more discoverable, more retrievable, and more useful. OA serves public funding agencies in a second way as well, by providing public access to the results of publicly-funded research.

Governments: As funders of research, governments benefit from OA in all the ways that funding agencies do (see previous entry). OA also promotes democracy by sharing government information as rapidly and widely as possible.

Citizens: OA gives them access to peer-reviewed research (most of which is unavailable in public libraries) and gives them access to the research for which they have already paid through their taxes. It also helps them indirectly by helping the researchers, physicians, manufacturers, technologists, and others who make use of cutting-edge research for their benefit.

Podcast: Open Access and Digital Scholarship at IUPUI: Conversations about Open Access at IUPUI by Dr. Richard Edwards and Kristi Palmer, defining OA, it's benefits, and the tools for digital scholarship available at IUPUI. Recorded October 13, 2009.